CORNWALL, Ont. -- Canadian researchers believe they have identified the source of the outbreak of Porcine Epidemic Diarrhea (PED) which has been causing so many problems for North American pig farmers.

PED is a coronavirus-like organism that affects young pigs, causing severe dehydration and usually death.

PED is confined to swine, not affecting any other livestock, nor humans, and is not a food danger.

First reported in England in 1971, by 2013 PED had spread throughout Europe and Asia.

On May 17, 2013, the first North American case was diagnosed at a pig farm in Iowa. The virus has since spread to some 23 other states, despite tightened farm security, and killed millions of piglets.

There were hopes that PED could be kept out of Canada, but the first case here was confirmed in Ontario on January 23, 2014, with subsequent cases following in Manitoba and Quebec, as well as many more Ontario farms.

In recent weeks, Canadian laboratory testing has suggested the source of the infection may be a blood plasma additive in a "nursery" ration used in both the U.S.A. and Canada.

While further testing takes place, the manufacturer has voluntarily recalled all existing feed stocks and has removed the use of plasma from the recipe for this feed.